Switchable fatty acid based CO2-effervescence ameliorated emulsification microextraction prior to high performance liquid chromatography for efficient analyses of toxic azo dyes in foodstuffs

Facile synthesis of amino-modified magnetic covalent organic framework for the efficient extraction and determination of anionic azo dyes in carbonated beverages

In this work, a novel magnetic covalent organic framework (COF (TpPa-NH2) @ Fe3O4) was prepared via two step by simple solvent method for the extraction of anionic azo dye residues in food. The as-prepared COF (TpPa-NH2) @ Fe3O4 nanocomposite was characterised by scanning electron microscope, transmission electron microscope, Fourier transform-infrared spectroscopy, X-ray diffraction and vibrating sample magnetometer. Before high-performance liquid chromatography with ultraviolet detection (HPLC-UV) determination, it was used as magnetic adsorbent for magnetic solid-phase extraction (MSPE) to extract and pre-concentrate three anionic azo dyes in carbonated beverage samples. The several key extraction and desorption parameters affecting the extraction recovery rate were investigated, including extraction time, pH of the solution, amount of material, adsorption time, elution solvent, pH of elution solvent, type of elution solvent, elution volume and elution time. Under optimised conditions, this method has good linearity between 5 and 500 μg L-1 (correlation coefficient > 0.9986). The limit of detection was 2.3-3.4 μg L-1. The recoveries of the samples were between 87.5 and 96.9%, and the relative standard deviation lower than 4.6%. The developed method has broad application prospects for the analysis of anionic azo dyes in carbonated beverages.

Trace-Level Determination of Triazole Fungicides Using Effervescence-Assisted Liquid-Liquid Microextraction Based on Ternary Deep Eutectic Solvent Prior to High-Performance Liquid Chromatography

A simple and sensitive preconcentration method, namely, effervescence-assisted liquid-liquid microextraction based on the ternary deep eutectic solvent method, was developed for enrichment of triazole fungicide residues prior to their determination by high-performance liquid chromatography coupled with UV detection. In this method, a ternary deep eutectic solvent (as extractant) was prepared by combination of octanoic acid, decanoic acid, and dodecanoic acid. The solution was well dispersed with sodium bicarbonate (as effervescence powder) without using auxiliary devices. In order to obtain relatively high extraction efficiency, analytical parameters were investigated and optimized. Under optimum conditions, the proposed method showed good linearity within the range of 1-1000 μg L^-1 with a coefficient for determination (R²) greater than 0.997. The low limits of detection (LODs) were in the range of 0.3-1.0 μg L^-1. The precisions were assessed from the relative standard deviations (RSDs) of retention time and peak area obtained from intra- (n = 3) and inter-day (n = 5 × 5) experiments, which were greater than 1.21 and 4.79%, respectively. Moreover, the proposed method provided high enrichment factors ranging from 112 to 142 folds. A matrix-match calibration method was used for analysis of real samples. Finally, the developed method was successfully applied for determination of the triazole fungicide in environmental water (near agricultural area), honey, and bean samples, and it represents a promising alternative method for analysis of triazoles. The recoveries of the studied triazoles were obtained in the range of 82-106% with an RSD less than 4.89.

Magnetic deep eutectic solvent-based dispersive liquid-liquid microextraction for enantioselectively determining chiral mefentrifluconazole in cereal samples via ultra-high-performance liquid chromatography

A simple, rapid, and efficient pretreatment method of mefentrifluconazole enantiomers in cereal samples was established by dispersive liquid-liquid microextraction coupled with ultra-high-performance liquid chromatography-diode array detector (UHPLC-DAD). In this study, a novel ternary magnetic deep eutectic solvent (MDES) [octyltrimethylammonium bromide][cobalt chloride][acetic acid] was synthesized as the extractant. Acetic acid was used as the dispersant to promote the in situ dispersion of binary MDES [octyltrimethylammonium bromide][cobalt chloride]. The microdroplets of binary MDES containing mefentrifluconazole were separated by an external magnet. Device-assisted dispersion and time-consuming centrifugation steps were eliminated to ensure simplicity and rapidity of the pretreatment. Good linearity ranging from 0.01 μg g^-1 to 2 μg g^-1 was obtained. The extraction recovery varied from 82.9 to 95.0%. The limit of detection was 0.003 μg g^-1. Finally, this established approach has been applied for the enantioselective detection of chiral mefentrifluconazole in corn, rice, wheat, millet, and sorghum samples.

Fast sequential multi element analysis of lead and cadmium in canned food samples using effervescent tablet-assisted switchable solvent based liquid phase microextraction (EA-SS-LPME) coupled with high-resolution continuum source flame atomic absorption spectrometry (HR-CS-FAAS)

An effervescent tablet-assisted switchable solvent based liquid phase microextraction (EA-SS-LPME) was developed for multi-element determination of Pb and Cd in various samples using high-resolution continuum source flame atomic absorption spectrometry (HR-CS-FAAS). The effervescent tablets were used for improving the extraction efficiency. Triethylamine as a hydrophobic solvent was switched to protonated triethylamine carbonate by CO₂ and used to extract dithizone complexes from samples. Calibration linearities were obtained from 0.06 to 10.0 mg L^-1 (Pb) and 0.02 to 1.50 mg L^-1 (Cd). LODs of the proposed method were 0.0195 (Pb) and 0.0068 (Cd). LOQs were 0.0649 mg L^-1 (Pb) and 0.0228 mg L^-1 (Cd) with %RSDs of 1.25%-1.69% (Pb) and 1.07%-1.64% (Cd). The proposed method was applied for the determination of Pb and Cd in water and canned food samples. The spiked recoveries were 82.3-119.0% (Pb) and 81.7-120.0% (Cd). In addition, the PF was 3.3, with EF at 1.4 (Pb) and 2.6 (Cd) obtained after extraction for under 8 min.

Hydrophobicity-switchable deep eutectic solvent-based effervescence-assisted dispersive liquid-liquid microextraction with solidification of floating droplets for HPLC determination of anthraquinones in fried Cassiae semen tea infusions

In this paper, a hydrophobicity-switchable deep eutectic solvent was evaluated for the first time as an efficient extractant in the effervescence-assisted dispersive liquid-liquid microextraction method combined with the solidification of floating droplets for HPLC determination of anthraquinones in fried Cassiae semen tea infusions. Prepared from choline chloride and octanoic acid, the deep eutectic solvent could be switched between hydrophobic and hydrophilic forms by pH adjustment. The dispersion of the extractant was assisted by in situ CO₂ produced from the effervescence reaction between H₂SO₄ and Na₂CO₃ without using any organic solvent or auxiliary equipment. Owing to the low melting/freezing point and low density compared with water, the extractant was solidified in an ice bath for the convenience of complete separation with the sample matrix. Some important parameters, such as species, molar ratio and volume of deep eutectic solvent, species and volume of effervescent agents were optimized to achieve the best extraction efficiency. Under the optimal conditions, extraction recoveries were obtained for four anthraquinones in the range of 91.1% to 111.9%. Relative standard deviations for intraday and interday precision were less than 3.3% and 4.0%, respectively. Greenness assessment demonstrated that the proposed method was greener than other reported methods for the determination of anthraquinones.

Cyclodextrin-based dispersive liquid-liquid microextraction for the determination of fungicides in water, juice, and vinegar samples via HPLC

Cyclodextrin-based dispersive liquid-liquid microextraction (CD-DLLME) was developed for the determination of triazole and strobilurin fungicides in water, juice, and vinegar samples using high-performance liquid chromatography-diode-array detection (HPLC-DAD). Undecanol, which is a green solvent, was selected as the extraction solvent. A cyclodextrin aqueous solution was chosen as the dispersion solvent and demulsifier to avoid the use of a toxic dispersion solvent and eliminate the centrifugation step. Dispersion and phase separation were completed within 1 and 60 s, respectively. The linear range of this method was 1 to 100 µg L^-1. The limits of detection were 0.3 μg L^-1 along with the preconcentration factor of 133 and enrichment factor of 124. The recovery was 83.2% to 103.2%. This pretreatment method was fast, simple, and environmentally friendly and was successfully applied to the analysis of triazole and strobilurin fungicide residues in water, juice, and vinegar samples.

Nonionic surfactants based hydrophobic deep eutectic solvents for liquid-liquid microextraction of Sudan dyes in tomato chili sauces

A new type of high-density hydrophobic deep eutectic solvents (DESs) were synthesized with nonionic surfactants as hydrogen bond acceptors and hexafluoroisopropanol (HFIP) as hydrogen bond donor. Brij-35 was selected as the optimal nonionic surfactant for the preparation of Brij-35-HFIP-DES (molar ratio 1:20). A vortex-assisted DES-based liquid-liquid microextraction method was proposed for determination of Sudan dyes in tomato chili sauces. The whole pretreatment process only needs 5 min and 1.1 mL of organic solvent. The method with HPLC-DAD shows high efficiency (enrichment factors 89-176 and extraction rates 61.0-74.6%) and good performance with linearity (R ≥ 0.9997) in 0.04-2 μg g^-1 range, detection limits of 0.0045-0.0118 μg g^-1, recoveries of 91.6-104.5% and intra-/inter-day precision below 8.0%. A "DES in water in DES" aggregate microstructure was observed in DES-rich phase. The proposed method is simple, quick, eco-friendly, and suits for the efficient extraction and accurate determination of Sudan dyes in tomato chili sauces.

Preparation of new hydrophobic deep eutectic solvents and their application in dispersive liquid-liquid microextraction of Sudan dyes from food samples

In this work, a new generation of hydrophobic deep eutectic solvents (DESs) was prepared using eugenol (as hydrogen bond donor) and benzyltriethylammonium bromide, benzyltributylammonium bromide, benzyltriethylammonium chloride and benzyltributylammonium chloride (as hydrogen bond acceptor) in different molar ratios. These DESs were applied to vortex-assisted dispersive liquid-liquid microextraction of Sudan dyes from food samples, followed by high-performance liquid chromatographic determination. The influencing parameters, including the type of DES, amount of DES, extraction time, solution pH and salt addition, were investigated and optimized. Under the optimized conditions, a linear range of 2-1000 ng mL^-1 with determination coefficients of <0.999 was obtained. Limits of detection and limits of quantification were in the range of 0.5 to 1 ng mL^-1 and 2 to 3 ng mL^-1, respectively. The proposed method was successfully used in the determination of Sudan dyes in chili sauce, chili powder and ketchup, and satisfactory recoveries of between 89.9 and 119.3% were obtained, with relative standard deviations in the range of 0.1-6.8%. The proposed method is simple, green and efficient, and can be applied to determine Sudan dyes in complex matrices.

Effervescence-assisted dual microextraction of PAHs in edible oils using lighter-than-water phosphonium-based ionic liquids and switchable hydrophilic/hydrophobic fatty acids

Herein, we developed a novel effervescence-assisted dual microextraction method, abbreviated as EM-LPSH, using lighter-than-water phosphonium-based ionic liquids (LPILs) and switchable hydrophilic/hydrophobic fatty acids (SHFAs). The EM-LPSH method was utilized for quick enrichment/extraction of polycyclic aromatic hydrocarbons (PAHs) in edible oils. Owing to lower density than water, LPILs used as the first extractant were floated on the upper layer of the aqueous phase, leading to a convenient separation/collection compared with traditional heavier-than-water imidazolium-based ionic liquids. Interestingly, SHFAs play triple functions: a dispersive solvent in the microextraction process, an acidic source in effervescent reaction, and the second extractant in dual microextraction, due to switchability from hydrophilicity to hydrophobicity. Consequently, the integration of LPILs with SHFAs greatly enhanced the extraction efficiency for PAHs owing to the quick dual microextraction process. Some important variables were rigorously optimized using a one-factor-at-a-time approach. Under optimized conditions, the EM-LPSH/HPLC-FLD method provided a wide linear range (0.07~0.63-200 μg kg^-1), satisfactory recovery (80.12-103.27%), and low limit of detection (0.02-0.19 μg kg^-1), as well as high intra-day and inter-day precision (0.03-6.55) for six PAHs in edible oils. By using certified reference material in olive oil samples (GBW10162), the recoveries ranged from 97.40 to 98.39%, demonstrating high accuracy and precision. According to the detected levels of PAHs in six unheated and heated oils, their edible safety was evaluated in detail. In short, the newly developed method is simple, convenient, and highly efficient, thereby showing great prospects for application in conventional monitoring of trace-level PAHs in edible oils.

Popping candy-assisted dispersive liquid-liquid microextraction for enantioselective determination of prothioconazole and its chiral metabolite in water, beer, Baijiu, and vinegar samples by HPLC

To simultaneously determine the enantiomers of prothioconazole and its chiral metabolite prothioconazole-desthio in water, beer, Baijiu, and vinegar samples by HPLC, a simple, fast, environmentally-friendly popping candy-assisted dispersive liquid-liquid microextraction technique was developed. A green medium-chain fatty acid (decanoic acid) and popping candy could be used as the extractant and solid dispersant respectively to avoid the use of toxic organic solvents. Decanoic acid was collected after extraction by solidification at room temperature. The linear range of this technique was from 27.1 to 1000 µg L^-1. The limits of detection and quantification were within the ranges of 8.1-11.2 μg L^-1 and 27.1-37.3 μg L^-1, respectively. The extraction recovery was 80.8% to 102.5% with the relative standard deviation ranged from 1.1 to 7.1%. This technique has been successfully applied to enantioselectively determine the residues of prothioconazole and prothioconazole-desthio in water, beer, Baijiu, and vinegar samples.

Effervescence-Assisted Microextraction-One Decade of Developments

Dispersive microextraction techniques are key in the analytical sample treatment context as they combine a favored thermodynamics and kinetics isolation of the target analytes from the sample matrix. The dispersion of the extractant in the form of tiny particles or drops, depending on the technique, into the sample enlarges the contact surface area between phases, thus enhancing the mass transference. This dispersion can be achieved by applying external energy sources, the use of chemicals, or the combination of both strategies. Effervescence-assisted microextraction emerged in 2011 as a new alternative in this context. The technique uses in situ-generated carbon dioxide as the disperser, and it has been successfully applied in the solid-phase and liquid-phase microextraction fields. This minireview explains the main fundamentals of the technique, its potential and the main developments reported.

Digital image colorimetry detection of carbaryl in food samples based on liquid phase microextraction coupled with a microfluidic thread-based analytical device

This research used a digital image colorimetry (DIC) method to detect carbaryl in food samples using effervescence-assisted liquid phase microextraction based on solidification of switchable hydrophilicity solvent combined with a microfluidic thread-based analytical device (EA-LPME-SSHS-μTAD). 1-naphthol, the hydrolysate of carbaryl, was extracted into octanoic acid by the adjustment of pH values of the sample solution and separated through solidification in an ice bath. Then 1-naphthol contained in the extracted solution was coupled with 4-methoxybenzenediazonlum tetrafluoroborate (MBDF) fixed on the μTAD to produce tangerine compounds. The inherent colour variation was captured by a smartphone and processed to calculate the intensity (I). Under the optimal conditions, the limit of quantification was within 0.020-0.027 mg kg^-1. The recovery was varied in the range from 92.3% to 105.9% with a relative standard deviation (RSD) below 5%. The developed method provides an alternative strategy to extract and detect pesticides for food samples.

Switchable-hydrophilicity solvent liquid-liquid microextraction versus dispersive liquid-liquid microextraction prior to HPLC-UV for the determination and isolation of piperine from Piper nigrum L

Switchable-hydrophilicity solvent liquid-liquid microextraction and dispersive liquid-liquid microextraction were compared for the extraction of piperine from Piper nigrum L. prior to its analysis by using high-performance liquid chromatography with UV detection. Under optimum conditions, limits of detection and quantitation were found as 0.2-0.6 and 0.7-2.0 μg/mg with the two methods, respectively. Calibration graphs showed good linearity with coefficients of determination (R² ) higher than 0.9962 and percentage relative standard deviations lower than 6.8%. Both methods were efficiently used for the extraction of piperine from black and white pepper samples from different origins and percentage relative recoveries ranged between 90.0 and 106.0%. The results showed that switchable-hydrophilicity solvent liquid-liquid microextraction is a better alternative to dispersive liquid-liquid microextraction for the routine analysis of piperine in food samples. A novel scaled-up dispersive liquid-liquid microextraction method was also proposed for the isolation of piperine providing a yield of 102.9 ± 4.9% and purity higher than 98.0% as revealed by NMR spectroscopy.